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Mr. Jeff Baker 3 - 16 June 2010 <br /> Stockton Terminals Technical Smittee • <br /> OW-46. During the first quarter, BTEX and MTBE concentrations were not detected <br /> above their WQOs. <br /> The First QMR contains a review of historical contaminant trends observed in select <br /> monitoring wells. Based on the review, STTC concludes that (1) the overall hydrocarbon <br /> concentration trends in groundwater beneath and downgradient of the Site appear <br /> relatively stable to decreasing and (2) results from the ozone injection monitoring program <br /> indicate the East and West remedial systems are effectively mitigating off-site migration of <br /> petroleum hydrocarbons. <br /> STTC member companies Tesoro and BP have conducted pilot studies of remedial <br /> technologies on their respective terminals. <br /> BP's 29 October 2009 Helium Tracer Study for Biosparging Feasibility Report <br /> summarized the results of a two-day A zone biosparge feasibility study on the BP <br /> facility to evaluate communication between potential injection and monitoring wells. <br /> Based on the results of the study, BP opted to evaluate alternate remedial <br /> technologies, including the possible use of passive diffusers. Our 11 March 2010 letter <br /> directed BP to submit this evaluation of alternate remedial technologies by 1 May 2010, <br /> including a method for mitigating MBAS. As we requested in our 11 March 2010 letter, <br /> BP will sample all BP wells and selected downgradient Port of Stockton wells for MBAS. <br /> Tesoro is proceeding with the 1-year, D zone, oxygen injection pilot study proposed in <br /> the 27 January 2009 Pilot Study Work Plan and Revised Contingency Plan. Instead of <br /> injecting oxygen, Tesoro recommends using a passive source of oxygen, such as the <br /> Waterloo EmitterTM, a down-hole apparatus which is connected to pressurized pure <br /> oxygen. During March 2010, injection wells TS/MW-3DR and TS/MW-4D were installed <br /> and developed. A helium tracer test will be conducted to confirm hydraulic <br /> communication between TS/MW-3DR and7S/MW-2D during the second quarter. <br /> Table 8 provides the results of the four-quarter background sampling study for total <br /> chromium, hexavalent chromium, vanadium, bromide, and bromate for Tesoro's <br /> proposed well TS-4R hydrogen peroxide (HPI) pilot test. Background groundwater <br /> monitoring was conducted in four wells, including TONT-3, TS-4R, TS/M-2, and TS-5. <br /> The results of background monitoring show that chromium and vanadium were <br /> detected in excess of their WQO of 0.05 milligrams per liter (mg/L). <br /> Potential injection wells TS/RW-1 and TS-4R are being monitored for the presence of <br /> free phase product. Product sheen was observed in TS/RW-1 during the first quarter. <br /> The First QMR states that the first HPI injection occurred during March 2010. <br /> Our comments are presented below. <br /> 1. While historic data show that decreasing trends exist in a few wells at the Site, such <br /> as TS/MW-1A and PS/MW-20C, such trends are displayed by a minority of the wells <br /> at the Site. Other on- and off-site wells, such as AR/MW-9A and PS/MW-18 which <br /> are identified in the First QMR as having order-of-magnitude reductions, are <br /> characterized by highly variable historic concentrations that previously featured the <br />